Aqueous solution precursors for making oxide thin films, and composition and method for making conductive oxide thin films therefrom

Abstract

Reagents and aqueous solutions thereof are described that are useful for aqueous processing to form thin films comprising metal oxides. A film, or layered film, may be incorporated into working devices where the thin film provides useful optical properties, electrical properties, or both.

We claim: 
     
         1 . A method for forming a conductive metal oxide thin film, comprising:
 preparing an aqueous solution;   applying the aqueous solution to a substrate to form a thin film; and   heating the substrate to form a conductive metal oxide thin film;   
       wherein the aqueous solution consists of
 water; and 
 a combination of metal salts, the combination comprising
 In(NO 3 ) 3  and at least one of SnCl 2  or SnF 2 where the indium salt and the tin salt(s) are provided in an atomic ratio of Sn:In of from 0.05:1 to 0.25:1; and 
 optionally a doping reagent selected from a cadmium or titanium dopant; 
 
 wherein the metal salts have a purity greater than 99%. 
 
     
     
         2 . The method according to  claim 1 , wherein the solution is applied to a substrate by spin coating, roll coating, spray coating, ink-jet printing, mist deposition, dye-slot coating, dip coating, doctor blade application, or combinations thereof. 
     
     
         3 . The method according to  claim 1 , wherein the metal oxide film comprises Sn:In 2 O 3 . 
     
     
         4 . The method of  claim 1 , wherein heating the substrate to form a conductive metal oxide thin film comprises forming a conductive metal oxide thin film having an RMS roughness value of from greater than zero to 3 nm. 
     
     
         5 . The method of  claim 4 , wherein the RMS roughness value is 1 nm or less. 
     
     
         6 . The method of  claim 1 , wherein heating the substrate to form a conductive metal oxide thin film comprises forming a conductive metal oxide thin film having a density of from 80% to 100% of the theoretical single crystal density of the material. 
     
     
         7 . The method of  claim 1 , wherein heating the substrate to form a conductive metal oxide thin film comprises forming a conductive metal oxide thin film having a density of from 80% to 100% of the theoretical single crystal density of the material and an RMS roughness value of from greater than zero to 3 nm. 
     
     
         8 . A conductive metal thin film produced by the method of  claim 1 , and having an RMS roughness value of from greater than zero to 3 nm. 
     
     
         9 . The conductive metal thin film according to  claim 8 , having an RMS roughness value of 1 nm or less. 
     
     
         10 . The conductive metal thin film according to  claim 8 , having a density of from 80% to 100% of the theoretical single crystal density of the material. 
     
     
         11 . A method, comprising:
 providing an aqueous solution;   applying the aqueous solution to a substrate to form a thin film by spin coating, roll coating, spray coating, ink-jet printing, mist deposition, dye-slot coating, dip coating, doctor blade application or combinations thereof;   heating the substrate to form a conductive metal oxide thin film; and   assembling a device comprising the substrate and conductive metal oxide thin film;   
       wherein the aqueous solution consists of
 water; and 
 a combination of metal salts, the combination comprising
 In(NO 3 ) 3  and at least one of SnCl 2  or SnF 2  where the indium salt and the tin salt(s) are provided in an atomic ratio of Sn:In of from 0.05:1 to 0.25:1; and 
 optionally a doping reagent selected from a cadmium or titanium dopant; 
 
 wherein the metal salts have a purity greater than 99%. 
 
     
     
         12 . The method of  claim 11 , wherein the oxide metal film comprises Sn:In 2 O 3 . 
     
     
         13 . The method of  claim 11 , wherein heating the substrate to form a conductive metal oxide thin film comprises forming a conductive metal oxide thin film having an RMS roughness value of from greater than zero to 3 nm. 
     
     
         14 . The method of  claim 13 , wherein the RMS roughness value is 1 nm or less. 
     
     
         15 . The method of  claim 11 , wherein heating the substrate to form a conductive metal oxide thin film comprises forming a conductive metal oxide thin film having a density of from 80% to 100% of the theoretical single crystal density of the material. 
     
     
         16 . The method of  claim 11 , wherein heating the substrate to form a conductive metal oxide thin film comprises forming a conductive metal oxide thin film having a density of from 80% to 100% of the theoretical single crystal density of the material and an RMS roughness value of from greater than zero to 3 nm. 
     
     
         17 . A device made according to the method of  claim 11 . 
     
     
         18 . The device of  claim 17 , wherein the device is a light emitting diode, a solar cell or a printed circuit.